The invention relates to a housing box for an electronic chip with biological probes, in particular for molecular analysis of DNA, said box comprising a flat support device provided with a window for access to a matrix of electrodes forming the active part of the chip.
A DNA chip is formed by a silicon substrate whereon one or a plurality of sequence(s) of biological probes formed by a matrix of electrodes and counter-electrodes each having small dimensions, about 50xc3x9750 microns, is(are) deposited. The arrangement of the probes at particular points of the substrate is performed according to known processes described in the documents U.S. Pat. No. 5,143,854 and WO 92/10092.
Each probe is moreover addressable by an electronic demultiplexing circuit integrated in the substrate so that the set of points of the matrix constitutes the image of a multitude of known DNA sequences relative to specific types of viruses. When molecular analysis is performed, the solution containing the patient""s DNA is deposited on the chip, and chemical bonds revealed by a fluorescence effect then form at certain points of the substrate.
It has been proposed according to the document WO 95/33846 to integrate a DNA chip in an enclosure formed by a flat support equipped with a cavity for access to the electrode matrix. The chip is generally stuck to the support by an adhesive, for example silicone or a cement, and the liquid (pyrrol-base reactive agent) and the DNA to be tested simply have to be inserted in the cavity to perform the analysis.
The object of the invention is to achieve an electrical connection between the biological chip and a connecting device accessible on the box and to obtain optimum protection of the chip with respect to a given environment.
The electronic chip housing box according to the invention is characterized in that:
the support device is formed by assembly of a first lower support and a second upper support, one whereof is equipped with a connector for activation of the chip,
a plurality of electrical connections extend along the assembly interface of the first and second supports between the connector and the chip,
electrical connecting means are arranged to ensure the continuity of the electrical connections with conducting strips of the chip,
and protective means are placed in the environment of the chip to obtain an electrical and biological insulating effect of the active part with respect to the input and output contacts of the connector.
According to one feature of the invention, the contacts of the connector and the electrical connections are made on one of the supports by means of a printed circuit or a conducting screen printing. It is also possible to use a flexible flat jumper added-on to one of the supports.
According to another feature of the invention, the electrical connecting means between the electrical connections and the chip are achieved either by soldering a conducting wire, or by melting a fusible tin-lead pad onto the chip, or by interposing double-sided adhesive strips made of conducting elastomer material.
According to a first embodiment, the box is characterized in that in that:
the connector and the electrical connections are located with the chip on the first lower support of the box,
the chip protrudes into the window arranged in the second upper support, which presents larger dimensions than the chip,
and a resin-base protective layer is deposited in said window to completely cover the electrical connecting means and the empty part of the cut-out surrounding the periphery of the chip.
According to a second embodiment, the box is characterized in that in that:
the connector and the electrical connections are arranged on the second upper support, which support is provided with the window having a smaller dimension than the chip,
the first lower support is equipped with a groove for housing the chip, the thickness of said chip being smaller than the depth of said groove,
and a bridging gap is arranged between the chip and the first support to receive a seal and electrical connecting means.
According to one feature of the invention, a visualization prism is advantageously incorporated in the window to divert an incident reading laser beam in a parallel direction above the probes of the chip.
The box houses a plurality of chips accessible via a single window and connected to a single connector. The chips can be integrated in a semi-conducting substrate.